1. Field of the Invention
The present invention relates to rotary encoders that are used in, for example, computer terminal devices, portable communication devices, or sound devices.
2. Description of the Related Art
The structure of a conventional rotary encoder will be described with reference to FIGS. 51-55. As best seen in FIG. 53, an insulating base 51 molded out of synthetic resin includes a base portion 51b having a hole 51a in the center portion thereof, a pair of arms 51c which extend at right angles from opposite ends of the base portion 51b, and supporting portions 51d formed on the ends of the arms 51c. The supporting portions 51d have holes formed therein by cutting away portions thereof.
Contactors 52, formed of metallic plates, have contact portions 52a and terminal portions 52b. Similarly, a common contactor 53, formed of a metallic plate, has a contact portion 53a and a terminal portion 53b. The contactors 52 and the common contactor 53 are disposed in a row and are embedded into and mounted to the base portion 51b. The contact portions 52a and the contact portion 53a are positioned within the hole 51a. The terminals 52b and the terminal 53b protrude outwardly from the base portion 51b. 
As best seen in FIG. 54, a resilient plate 54, formed of a metallic plate, is disposed in a row with the contactors 52 and the common contactor 53 and is also mounted to the base portion 51b. 
As best seen in FIGS. 52 and 55, a cylindrical rotary member 55 comprises a cylindrical portion 56 molded out of synthetic resin, and a code member 57 provided at the outer circumferential surface of the cylindrical portion 56. The code member 57 is formed of an electrically conductive material. In particular, the code member 57 is formed by molding electrically conductive resin twice.
A common pattern 57a, a comb-like code pattern 57b, and a clicking uneven portion 56a are formed at the outer circumferential surface of the cylindrical portion 56 so as to be disposed in a row along the direction of the rotational axis.
Shafts 56b are provided at both ends of the cylindrical portion 56. A noncircular hole 56c is formed in the center portion of the cylindrical portion 56.
The rotary member 55 is rotatably mounted to the insulating base 51 by snapping the shafts 56b into the supporting portions 51d of the pair of arms 51c. When the rotary member 55 has been mounted, the contact portion 53a of the common contactor 53 is in contact with the common pattern 57a, the contact portions 52a of the contactors 52 are in contact with the code pattern 57b, and the resilient plate 54 is in resilient contact with the uneven portion 56a. 
A dome-shaped cover 58 is mounted to the insulating base 51 so as to cover the rotary member 55, whereby the body E2 of the encoder is constructed.
As shown in FIG. 53, the body E2 of the encoder is mounted on a printed circuit board P2 by placing the bottom surface of the insulating base 51 on the printed board P2. The terminal portions 52b of the contactors 52 and the terminal portion 53b of the common contactor 53 are inserted through a hole in the printed board P2 and are soldered onto a wiring pattern (not shown).
The conventional rotary encoder having the above-described structure operates as follows. When an actuating shaft (not shown) is inserted in the hole 56c of the rotary member 55 and is rotated from the outside, the rotary member 55 is likewise rotated. When the rotary member 55 is rotated, the code member 57 is also rotated. Although the common contact 53 is always in contact with the common pattern 57a, the contactors 52 are only in intermittent contact with the code pattern 57b. This causes a pulse signal to be generated between the common contactor 53 and the contactors 52 as the rotary member 55 is rotated.
The rotation of the rotary member 55 causes the resilient plate 54 to engage and disengage with the uneven portion 56a, thereby generating a clicking of the rotary member 55.
However, the conventional rotary encoder is formed by molding the code member 57 out of electrically conductive resin. Consequently, the molding of the code member 57 is difficult and expensive to produce. In addition, since the common pattern 57a, the code pattern 57b, and the clicking uneven portion 56a are disposed in a row along the outer circumferential surface of the rotary member 55, the conventional rotary encoder is relatively large in the direction of the rotational axis of the rotary member 55.
Accordingly, it is an object of the present invention to provide a small, low-cost rotary encoder that overcomes the above-referenced problems.
To this end, according to a first aspect of the present invention, there is provided a rotary encoder comprising a rotary member which is formed of an insulating material and which has at least one of a columnar shape, a cylindrical shape, and a truncated conical shape; a code member mounted to the rotary member and formed of a metallic plate; and a plurality of contactors which contact the code member. In the rotary encoder, the code member comprises an annular plate-shaped portion and a plurality of tongues formed by bending the plate-shaped portion. The plate-shaped portion is disposed in a direction perpendicular to the direction of the rotational axis of the rotary member. The tongues are disposed so as to be exposed at a circumferential surface side of the rotary member.
Accordingly, since the code member comprising an annular plate-shaped portion and the plurality of tongues are formed of a metallic plate, it is possible to provide a low-cost rotary encoder which can be easily produced with high productivity as compared to the conventional device wherein a molded electrically conductive resin is used.
In addition, since the plate-shaped portion is disposed in a direction perpendicular to the rotational axial direction of the rotary member, and the tongues are disposed so as to be exposed at the circumferential surface side of the rotary member, a proper spacing along the rotational axis is obtained for the plate-shaped portion, thereby permiting the manufacture of a small rotary encoder.
The tongues of the code member may be formed by bending from an outer peripheral portion of the plate-shaped portion. This structure is therefore effective when the tongues need to be made long.
The tongues of the code member may alternatively be by bending from an inner peripheral portion of the plate-shaped portion. This enables material from the metallic plate to be eliminated, making it possible to provide a small, low-cost rotary encoder.
The tongues of the code member may be disposed at an outer circumferential surface side of the rotary member. Accordingly, the contactors can be freely disposed, making it possible to provide a rotary encoder adapted to various forms.
The rotary member may have a cylindrical shape, and the tongues of the code member may be disposed at an inner circumferential surface side of the rotary member. Accordingly, the code member can be made small, making it possible to provide a small rotary encoder.
When a rotary encoder comprises a rotary member, a code member, and a plurality of contactors, the code member may be embedded into the rotary member in order to be mounted to the rotary member. Accordingly, the manufacturing process can be simplified, and improved productivity is achieved, making it possible to provide a low-cost rotary encoder.
When a rotary member comprises a rotary member, a code member, and a plurality of contactors, the tongues of the code member may be fitted into a groove formed in the circumferential surface side of the rotary member in order to mount the code member to the rotary member. Accordingly, it is possible to easily adapt to various forms of the code member, so that an adaptable rotary encoder can be provided.
When the code member is embedded into the rotary member, the plate-shaped portion may be disposed at an end surface side of the rotary member, which extends perpendicular to the axis of rotation of the rotary member. Accordingly, the plate-shaped portion can be supported by a die during the manufacturing process. This makes it possible to provide a rotary encoder of improved quality.
When a rotary member comprises a rotary member, a code member, and a plurality of contactors, the contactors may be brought into contact with the plate-shaped portion and the tongues, the plate-shaped portion may be a common contact, and the tongues may be change-over contacts. Accordingly, the amount of space in the direction of the rotational axis can be reduced, making it possible to provide a rotary encoder of reduced size.
According to a second aspect of the present invention, there is provided a rotary encoder comprising a rotary member which is formed of an insulating material and which has at least one of a columnar shape, a cylindrical shape, or a truncated conical shape; a code pattern provided at an external surface of the rotary member; and a contactor which contacts the code pattern. The code pattern is formed at a circumferential surface of the rotary member. A common pattern, which is electrically conductive with the code pattern, is formed at an end surface of the rotary member. A common contactor is in contact with the common pattern.
Accordingly, since the code pattern is formed at the circumferential surface of the rotary member, and the common pattern which is electrically conductive with the code pattern is formed at an end surface of the rotary member, the code pattern can be made long, and the length of the rotary member in the direction of the rotational axis can be made smaller than that of a rotary member of a conventional rotary encoder. Therefore, a reduced size rotary encoder can be provided.
The code pattern may be formed at an outer circumferential surface of the rotary member. Accordingly, the code pattern can be made long, and the contactors can be freely disposed, making it possible to provide a rotary encoder which can adapt to various forms.
When a rotary encoder comprises a rotary member, a code pattern, and a contactor, the rotary member may have a cylindrical shape, and the code pattern may be formed at an inner circumferential surface of the rotary member. Accordingly, the height of the contactor can be reduced, making it possible to provide a smaller rotary encoder.
When a rotary encoder comprises a rotary member, a code pattern, and a contactor, a plurality of the contactors may be disposed opposite each other, with the circumferential surface of the rotary member being disposed therebetween, and the common contactor may be disposed so as to oppose the end surface of the rotary member. Accordingly, they are not disposed in a row along the rotational axis with respect to each other, so that a proper space factor along the rotational axis can be obtained, making it possible to provide a rotary encoder of reduced size.
When a plurality of the contactors are disposed opposite each other, with the circumferential surface of the rotary member being disposed therebetween, and the common contactor is disposed so as to oppose the end surface of the rotary member, the contactors and the common contactor may be mounted to an insulating base formed of an insulating material, and may be provided so as to extend in the direction of the rotary member with the insulating base as a reference surface. Accordingly, the reference of the contactors and the common contactor in the height direction is the insulating base, so that the precision with which they are mounted relative to each other is increased. Therefore, it is possible to provide a highly precise rotary encoder.
According to a third aspect of the present invention, there is provided a rotary encoder comprising a rotary member which is formed of an insulating material and which has at least one of a columnar shape, a cylindrical shape, and a truncated conical shape; a code pattern formed at an external surface of the rotary member; and a plurality of contactors which contact the code pattern. In the rotary encoder of this embodiment, the code pattern is formed at a circumferential surface of the rotary member. A clicking uneven portion is formed at one of the end surfaces of the rotary member. An engaging member is made to engage and disengage the uneven portion in order to form a click mechanism.
Accordingly, since the code pattern is formed at the circumferential surface of the rotary member, and the clicking uneven portion is formed at one end surface of the rotary member to allow the engaging member to engage and disengage the uneven portion so as to construct a click mechanism, the code pattern can be made long, and the length of the rotary member in the direction of the rotational axis can be made smaller than that of a rotary member of a conventional rotary encoder. Therefore, it is possible to provide a rotary encoder of reduced size.
A common pattern which is electrically conductive with the code pattern may be formed at the other end surface of the rotary member which opposes the one end surface of the rotary member, and a common contactor may be in contact with the common pattern. Accordingly, the space in the rotational axial direction at the common pattern can be reduced, making the size in the rotational axial direction even smaller. Therefore, it is possible to provide a rotary encoder of reduced size.
When a common pattern which is electrically conductive with the code pattern is formed at the other end surface of the rotary member that opposes the one end surface of the rotary member, and a common contactor is in contact with the common pattern, the plurality of contactors may be disposed opposite each other, with the circumferential surface of the rotary member being disposed therebetween, the engaging member may be disposed so as to oppose the one end surface of the rotary member, and the common contactor may be disposed so as to oppose the other end surface of the rotary member. Accordingly, these components are not disposed in a row along the rotational axis with respect to each other, so that a proper space factor can be obtained. This makes it possible to provide a rotary encoder of reduced size.
When the plurality of contactors are disposed opposite each other, with the circumferential surface of the rotary member being disposed therebetween, the engaging member is disposed so as to oppose the one end surface of the rotary member, and the common contactor is disposed so as to oppose the other end surface of the rotary member, the contactors and the common contactor may be mounted to an insulating base formed of an insulating material, and the contactors, the common contactor, and the engaging member may be provided so as to extend in the direction of the rotary member, with the insulating base as a reference surface. Accordingly, the reference of the contactors, the common contactor, and the engaging member in the height direction is the insulating base, so that the precision with which they are mounted relative to each other can be increased. Therefore, it is possible provide a highly precise rotary encoder.